First shot at making indexer decorator chainable

gistfile1.py

class indexer(adapter):
    [...]
    def __call__(self, callable):
        if type(callable) is DelegatingIndexerFactory:
            factory = DelegatingIndexerFactory(callable.callable)
        else:
            factory = DelegatingIndexerFactory(callable)
        adapted = adapter.__call__(self, factory)
        print 'indexer.__call__', self, callable, factory, adapted #DBG 
        return adapted